Question

我有一个查询，它返回以下表格中的结果：

Element  READING1  READING2 READING3
---------------------------------------
1        0.25      1.5      3.5
2        1.3       2.3      5.5
3        4.5       5.5      4.3
..        ..       ..       ..   
n        1.5       2.3      5.5
---------------------------------------

我希望以下列形式输出：

           1        2          3    ..     n
         ---------------------------------------
READING1  0.25     1.3        4.5   ..    1.5
READING2  1.5      2.3        5.5   ..    2.3
READING3  3.5      5.5        4.3   ..    5.5

，我必须转移表格。我尝试过以下方式使用Oracle Pivot：

WITH T AS (
SELECT  Element,READING1 from ZZZ;    ----(1)
)
SELECT * FROM T
PIVOT( MAX(READING1) FOR ELEMENT IN (1,2,3,..n))     ----(2)

这只给了READING1的结果，但是我无法正确地产生所有读数的结果。任何帮助都将受到高度赞赏。

先谢谢，

最诚挚的问候， KUNAL

Answer 1

您已关闭 - 您想要的是UNPIVOT和PIVOT的组合：

with T AS (
  select 1 as element, 1.1 as reading1, 1.2 as reading2, 1.3 as reading3 from dual union all
  select 2 as element, 2.1 as reading1, 2.2 as reading2, 2.3 as reading3 from dual union all
  select 3 as element, 3.1 as reading1, 3.2 as reading2, 3.3 as reading3 from dual 
)
select * from (
  select * from t
  unpivot (reading_value
    for reading_name in ("READING1", "READING2", "READING3")
    )
  pivot(max(reading_value) for element in (1,2,3)
  )
)
order by reading_name

此查询

将列 reading1，reading2，reading3转换为单独的行（名称转换为 reading_name ，值转换为 reading_value < / em>的）;这给了我们一行（element，reading_name）

将行 1,2 *，3（元素的值）转换为列＆＃39; 1＆＃39;，＆＃39; 2＆＃39 ;，＆＃39; 3＆＃39 ;;这给了我们每read_name一行

<强>更新

如果在运行时之前不知道元素列表（例如，因为用户可以选择它们），则需要更动态的方法。这是一个解决方案，它为给定的元素列表动态创建SQL语句，并为结果集使用sys_refcursor。

-- setup table create table T AS select 1 as element, 1.1 as reading1, 1.2 as reading2, 1.3 as reading3 from dual union all select 2 as element, 2.1 as reading1, 2.2 as reading2, 2.3 as reading3 from dual union all select 3 as element, 3.1 as reading1, 3.2 as reading2, 3.3 as reading3 from dual ; / declare l_Elements dbms_sql.Number_Table; function pivot_it(p_Elements in dbms_sql.Number_Table) return sys_refcursor is l_SQL CLOB := empty_clob(); l_Result sys_refcursor; begin l_SQL := ' select * from ( select * from t unpivot (reading_value for reading_name in ("READING1", "READING2", "READING3") ) pivot(max(reading_value) for element in ('; for i in 1 .. p_Elements.count loop l_SQL := l_SQL || to_char(p_Elements(i)) || ','; end loop; -- remove trailing ',' l_SQL := regexp_replace(l_SQL, ',$'); l_SQL := l_SQL || ') ) )'; dbms_output.put_line(l_SQL); open l_Result for l_SQL; return l_Result; end; begin l_Elements(1) := 1; l_Elements(2) := 2; -- uncomment this line to get all 3 elements -- l_Elements(3) := 3; -- return the cursor into a bind variable (to be used in the host environment) :p_Cursor := pivot_it(l_Elements); end;

如何使用从此函数返回的光标取决于您使用的环境 - 在SQL / Plus中，您只需打印它，以及大多数编程语言＆＃39; Oracle绑定支持它开箱即用。

CAVEAT：虽然此代码适用于所提供的数据，但它甚至缺少基本的错误检查。这一点尤为重要，因为动态SQL始终是SQL注入攻击的可能目标。

在Oracle 11g中转置查询结果

1 个答案: